added program and result of cls09

src/cls09/Makefile

@@ -0,0 +1,14 @@
+include ../common.mk
+
+PROJECT_NAME:=cls09
+
+TGTS:=$(patsubst %.c,%,$(wildcard *.c))
+
+all: $(TGTS)
+
+%: %.c
+	@mkdir -p $(BUILD_PATH)/$(PROJECT_NAME)
+	$(CC) $(CFLAGS) $^ -o $(BUILD_PATH)/$(PROJECT_NAME)/$@
+
+clean:
+	$(RM) -drf $(BUILD_PATH)/$(PROJECT_NAME)

src/cls09/a1.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+void adjust_point(int *n) {
+    if (*n < 0) {
+        *n = 0;
+    } else if (*n > 100) {
+        *n = 100;
+    }
+}
+
+int main(void) {
+    int d = 0;
+
+    printf("Input integer: ");
+    scanf("%d", &d);
+
+    adjust_point(&d);
+    printf("Result: %d\n", d);
+
+    return 0;
+}

src/cls09/a2.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define BUFFSZ 32
+
+const int DAYS_IN_MONTH[12] = {
+    31,
+    28,
+    31,
+    30,
+    31,
+    30,
+    31,
+    31,
+    30,
+    31,
+    30,
+    31
+};
+
+void increment_date(int *year, int *month, int *day) {
+    (*day)++;
+    
+    if (*day > DAYS_IN_MONTH[*month - 1]) {
+        *day = 1;
+        (*month)++;
+    }
+
+    if (*month > 12) {
+        *month = 1;
+        (*year)++;
+    }
+}
+
+void decrement_date(int *year, int *month, int *day) {
+    (*day)--;
+    
+    if (*day < 1) {
+        (*month)--;
+        if (*month < 1) {
+            *month = 12;
+            (*year)--;
+        }
+        *day = DAYS_IN_MONTH[*month - 1];
+    }
+}
+
+int main(void) {
+    char *buff = (char*)malloc(sizeof(char) * BUFFSZ);
+
+    int m, d, y;
+    printf("Input date in mm/dd/yyyy: ");
+    fgets(buff, BUFFSZ, stdin);
+    sscanf(buff, "%d/%d/%d", &m, &d, &y);
+
+
+    char opr_in;
+    while (1) {
+        printf("Select operation [+/-]: ");
+        opr_in = getc(stdin);
+        if (opr_in == '+') {
+            increment_date(&y, &m, &d);
+            printf("Tomorrow is %02d/%02d/%4d\n", m, d, y);
+            break;
+        } else if (opr_in == '-') {
+            decrement_date(&y, &m, &d);
+            printf("Yesterday was %02d/%02d/%4d\n", m, d, y);
+            break;
+        } else {
+            printf("Error: Please input correct operation mode.\n");
+        }
+    }
+
+
+    return 0;
+}

src/cls09/a3.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+void swap(int *a, int *b) {
+    int t = *a;
+    *a = *b;
+    *b = t;
+}
+
+void sort3(int *x, int *y, int *z) {
+    if (*x > *y) swap(x, y);
+    if (*y > *z) swap(y, z);
+    if (*x > *y) swap(x, y);
+}
+
+int main(void) {
+    int a,b,c;
+
+    printf("Input 3 integers separated by ',': ");
+    scanf("%d,%d,%d", &a, &b, &c);
+
+    sort3(&a, &b, &c);
+
+    printf("Result: %d, %d, %d\n", a, b, c);
+
+    return 0;
+}